The invention relates to moisture curing sealant compositions that include silane functional poly-α-olefins.
Insulating glass assemblies such as insulating glass units and insulating sash assemblies often include a pair of glass sheets maintained in a fixed spaced relation to each other by a spacing and sealing composition that extends around the periphery of the inner facing surfaces of the glass sheets to define a sealed and insulating space between the glass sheets. In the case of insulating sash assemblies, the glass panes are adhered to a frame. The glass sheets are usually attached to the structure by a sealant or adhesive composition. The sealant or adhesive composition is also used to seal the edges of the insulating glass assembly so as to establish a barrier that prevents moisture from penetrating into the interior of the assembly. Insulating sash assemblies are described, e.g., in U.S. Pat. No. 6,286,288.
Sealants used in glass assemblies are referred to as “primary” sealants and “secondary” sealants. Primary sealants provide a moisture barrier function between the two substrates of the assembly. Secondary sealants provide an adhesive bond between two substrates in the assembly. Some sealants are formulated to provide both primary and secondary sealant functions.
Two classes of sealants used in the insulating glass industry are chemically curing thermoset compositions, and thermoplastic one-part hot melt butyl-type compositions. Chemically curing systems often include liquid polysulphides, polyurethanes, mercaptan-modified polyether polyurethanes and two-component silicones. Thermoplastic compositions, which are also referred to as “non-curing systems,” are often polyisobutylene-polyisoprene copolymer rubber-based hot melt compositions.
Chemical curing thermoset sealants are usually two-component systems in which the components are combined, at room temperature, just prior to application. The sealants tend to cure slowly. The slow cure can increase manufacturing time and costs.
Non-curing hot melt systems generally set faster and can overcome the disadvantage of having a slow cure time, but hot melts are more susceptible to fluctuations in ambient temperature and may soften with high temperatures or stiffen with cold and do not develop as high ultimate bond strengths in comparison to curing systems.
Other sealant compositions that have been developed include a one part sealant that includes thermoplastic hot melt resin and an atmosphere curing resin capable of polymerizing upon exposure to ambient atmosphere. Some of these compositions cure to such a hardness that, when used as a sealant in a window construction, they create a tension between two substrates when the substrates are of differing materials, e.g., glass and polymer.